2. Our Solar System I Origins of the Solar System Astronomy 12

3. Learning Outcomes (Students will…) -Explain the theories for the origin of the solar system -Distinguish between questions that can be answered by science and those that cannot, and between problems that can be solved by technology and those that cannot with regards to solar system formation. -Estimate quantities of distances in parsec. Estimate the age of the solar system. -Describe and apply classification systems and nomenclature used in the sciences. Classify planets as terrestrial vs. Jovian, inner vs. outer, etc. Classify satellites. Classify meteoroid, asteroid, dwarf planet, planet. Classify comets as long period vs. short period. etc -Formulate operational definitions of major variables. Given data such as diameter and density describe the properties that divide the planets and moons into groups. -Tools and methods used to observe and measure the inner and the outer planets and the minor members of the solar system

4. Our Solar System Our solar system is made up of: Sun Sun Eight planets Eight planets Their moons Their moons Asteroids & Meteroids Asteroids & Meteroids Comets Comets

6. Inner Planets The inner four rocky planets at the center of the solar system are: Mercury Mercury Venus Venus Earth Earth Mars Mars

7. Mercury Planet nearest the sun Planet nearest the sun Second smallest planet Second smallest planet Covered with craters Covered with craters Has no moons or rings Has no moons or rings About size of Earth’s moon About size of Earth’s moon

8. Venus Sister planet to Earth Sister planet to Earth Has no moons or rings Has no moons or rings Hot, thick atmosphere Hot, thick atmosphere Brightest object in sky besides sun and moon (looks like bright star) Brightest object in sky besides sun and moon (looks like bright star) Covered with craters, volcanoes, and mountains Covered with craters, volcanoes, and mountains

9. Earth Third planet from sun Third planet from sun Only planet known to have life and liquid water Only planet known to have life and liquid water Atmosphere composed of Nitrogen (78%), Oxygen (21%), and other gases (1%). Atmosphere composed of Nitrogen (78%), Oxygen (21%), and other gases (1%).

10. Mars Fourth planet from sun Fourth planet from sun Appears as bright reddish color in the night sky Appears as bright reddish color in the night sky Surface features volcanoes and huge dust storms Surface features volcanoes and huge dust storms Has 2 moons: Phobos and Deimos Has 2 moons: Phobos and Deimos

14. Asteroid Belt Separates the inner, terrestrial planets from the outer, Jovian planets Separates the inner, terrestrial planets from the outer, Jovian planets Contains ~100,000 asteroids. Contains ~100,000 asteroids. Largest known asteroid: 4 Vesta Largest known asteroid: 4 Vesta Largest object : Ceres (dwarf planet) Largest object : Ceres (dwarf planet)

15. Outer Planets The outer planets composed of gas are : Jupiter Jupiter Saturn Saturn Uranus Uranus Neptune Neptune

16. Jupiter Largest planet in solar system Largest planet in solar system Brightest planet in sky Brightest planet in sky At last count, 65 moons: 5 visible from Earth At last count, 65 moons: 5 visible from Earth Strong magnetic field Strong magnetic field Giant red spot Giant red spot Rings have 3 parts: Halo Ring, Main Ring, Gossamer Ring Rings have 3 parts: Halo Ring, Main Ring, Gossamer Ring

18. Saturn 6 th planet from sun 6 th planet from sun Beautiful set of rings Beautiful set of rings 62 moons 62 moons Largest moon, Titan, Largest moon, Titan, Easily visible in the night sky Easily visible in the night sky Voyager explored Saturn and its rings. Voyager explored Saturn and its rings.

19. Uranus 7 th planet from sun 7 th planet from sun Has a faint ring system Has a faint ring system 27 known moons 27 known moons Covered with clouds Covered with clouds Uranus sits on its side with the north and south poles sticking out the sides. Uranus sits on its side with the north and south poles sticking out the sides.

20. Neptune 8 th planet from sun 8 th planet from sun Discovered through math Discovered through math 12 known moons 12 known moons Triton largest moon Triton largest moon Great Dark Spot thought to be a hole, similar to the hole in the ozone layer on Earth Great Dark Spot thought to be a hole, similar to the hole in the ozone layer on Earth

22. A Dwarf Planet Pluto is a small solid icy planet is smaller than the Earth's Moon. Pluto is a small solid icy planet is smaller than the Earth's Moon.

23. Pluto Never visited by spacecraft Never visited by spacecraft Orbits very slowly Orbits very slowly Charon, its moon, is very close to Pluto and about the same size Charon, its moon, is very close to Pluto and about the same size

24. Two Types of Planets: Terrestrial and Jovian Why?

25. Sun, a star, at the center Inner (rocky) Planets (Mercury, Venus, Earth, Mars) ~ 1 AU Asteroid Belt ~ 3 AU Outer (gaseous) Planets (Jupiter, Saturn, Neptune, Uranus) ~ 5-40 AU Kuiper Belt ~ 30 to 50 AU -includes Pluto Oort Cloud ~ 50,000 AU What does the solar system look like from far away?

26. Bode’s Law A rough rule that predicts the spacing of the planets in the Solar System To find the mean distances of the planets, beginning with the following simple sequence of numbers: 0 3 6 12 24 48 96 192 384 With the exception of the first two, the others are simple twice the value of the preceding number. Add 4 to each number: 4 7 10 16 28 52 100 196 388 Then divide by 10: 0.4 0.7 1.0 1.6 2.8 5.2 10.0 19.6 38.8 Planet Actual Distance (AU) Bode’s Law Mercury0.390.4 Venus0.720.7 Earth1.001.0 Mars1.521.6 Jupiter5.205.2 Saturn9.5410.0 Uranus19.219.6 Neptune30.138.8 Works for moons too!

29. Asteroids Small bodies Small bodies Believed to be left over from the beginning of the solar system billions of years ago Believed to be left over from the beginning of the solar system billions of years ago 100,000 asteroids lie in belt between Mars and Jupiter 100,000 asteroids lie in belt between Mars and Jupiter Largest asteroids have been given names Largest asteroids have been given names

31. Most asteroids are located in two regions: Asteroid belt Orbit of Jupiter… the Hildas (the orange "triangle" just inside the orbit of Jupiter) and the Jovian Trojans (green). The group that leads Jupiter are called the "Greeks" and the trailing group are called the "Trojans" Hildas Jovian Trojans Where are the asteroids?

35. Comets Small icy bodies Small icy bodies Travel past the Sun Travel past the Sun Give off gas and dust as they pass by Give off gas and dust as they pass by

37. Anatomy of a Comet

39. Where are the comets? Kuiper Belt A large body of small objects orbiting (the short period comets <200 years) the Sun in a radial zone extending outward from the orbit of Neptune (30 AU) to about 100 AU. Pluto maybe the biggest of the Kuiper Belt object. Oort Cloud Long Period Comets (period > 200 years) seems to come mostly from a spherical region at about 50,000 AU from the Sun.

58. Key Ideas Properties of the Planets: All of the planets orbit the Sun in the same direction and in almost the same plane. Most of the planets have nearly circular orbits. The four inner planets are called terrestrial planets. They are relatively small (with diameters of 5000 to 13,000 km), have high average densities (4000 to 5500 kg/m3), and are composed primarily of rocky materials. The four giant outer planets are called Jovian planets. They have large diameters (50,000 to 143,000 km) and low average densities (700 to 1700 kg/m3) and are composed primarily of light elements such as hydrogen and helium.

59. Key Ideas Satellites and Small Bodies in the Solar System: Besides the planets, the solar system includes satellites of the planets, asteroids, comets, and trans-Neptunian objects. Seven large planetary satellites (one of which is our Moon) are comparable in size to the planet Mercury. The remaining satellites of the solar system are much smaller.

60. Key Ideas Asteroids are small, rocky objects, while comets and trans-Neptunian objects are made of ice and rock. All are remnants left over from the formation of the planets. Most asteroids are found in the asteroid belt between the orbits of Mars and Jupiter, and most trans-Neptunian objects lie in the Kuiper belt outside the orbit of Neptune. Pluto is one of the largest members of the Kuiper belt.

61. Key Ideas Spectroscopy and the Composition of the Planets: Spectroscopy, the study of spectra, provides information about the chemical composition of objects in the solar system. The spectrum of a planet or satellite with an atmosphere reveals the atmosphere’s composition. If there is no atmosphere, the spectrum indicates the composition of the surface. The substances that make up the planets can be classified as gases, ices, or rock, depending on the temperatures at which they solidify.

62. Key Ideas Impact Craters: When an asteroid, comet, or meteoroid collides with the surface of a terrestrial planet or satellite, the result is an impact crater. Geologic activity renews the surface and erases craters, so a terrestrial world with extensive cratering has an old surface and little or no geologic activity. Because geologic activity is powered by internal heat, and smaller worlds lose heat more rapidly, as a general rule smaller terrestrial worlds are more extensively cratered.

63. Key Ideas Magnetic Fields and Planetary Interiors: Planetary magnetic fields are produced by the motion of electrically conducting liquids inside the planet. This mechanism is called a dynamo. If a planet has no magnetic field, that is evidence that there is little such liquid material in the planet’s interior or that the liquid is not in a state of motion. The magnetic fields of terrestrial planets are produced by metals such as iron in the liquid state. The stronger fields of the Jovian planets are generated by liquid metallic hydrogen or by water with ionized molecules dissolved in it.